Cooling actives, such as menthol and the like, have been used in personal care formulations to provide a variety of benefits. Besides the largely cosmetic benefits of fresh sensation and/or scent left on skin after topical use, cooling actives may also have local anaesthetic and counterirritant qualities.
Unfortunately, however, cooling actives may be difficult to formulate at high concentration in personal care formulations and/or there may be safety and environmental constraints on their use at levels high enough to produce a noticeable effect on topical application.
Thus the present inventors have recognised a need to improve the efficiency of deposition of cooling actives from personal care formulations to address one or more of these issues. To this end the present inventors have found that, compared with conventional deposition polymers such as cationic guar, certain copolymers can enhance deposition of cooling actives. In particular, the present inventors have found that copolymers comprising acrylamidopropyltrimonium chloride are especially efficacious.
One such copolymer is the acrylamidopropyltrimonium chloride/acrylamide copolymer commercially available from Ashland as N-Hance SP-100®, wherein the same has been described for use in delivering actives such as silicone, emollients and antimicrobial agents such as zinc and selenium onto hair and skin by forming coacervates with anionic surfactants. Such copolymers are also described, for example, in WO 2011/003068 A1 (HERCULES INC.). However, we have now found that copolymer comprising acrylamidopropyltrimonium chloride can improve the delivery of cooling actives and that such delivery can be effective even where the copolymer is not employed in great excess compared with the amount of cooling active.